/*
 * Copyright 2021 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package javaemul.internal;

import jsinterop.annotations.JsType;

/** Contains logics for calculating hash codes in JavaScript. */
@JsType
public class HashCodes {

  public static int getIdentityHashCode(Object o) {
    return o == null ? 0 : getObjectIdentityHashCode(o);
  }

  private static int nextHash;

  public static int getObjectIdentityHashCode(Object o) {
    return o.$systemIdentityHashCode != 0
        ? o.$systemIdentityHashCode
        : (o.$systemIdentityHashCode = ++nextHash);
  }
}
